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Nuclear Reactors and Production

ISIS Course-Week 4 October 23, 2014 Nuclear Reactors

• A is an apparatus or in which can be made to undergo a controlled, self-sustaining with the consequent release of energy. The Basic Parts of a Reactor http://en.wikipedia.org/wiki/Magnox

• region • Heat removal equipment • Control system • Refueling capability Purposes of Reactors

• Nuclear reactors are used for civilian purposes to – generate electricity – produce heat via – produce for medical, industrial, or research purposes – conduct research – propel surface ships, such as ice-breakers • Nuclear reactors are also used for military purposes to – produce plutonium for nuclear weapons – produce for nuclear weapons – propel military and surface ships – power aircraft and rockets (abandoned) Classification of Reactors

• Power reactors – typically civilian, almost all now generate electricity. Some produced steam for . Typically make large quantities of reactor-grade plutonium. • Research reactors – typically civilian aimed at making isotopes or conducting research. – In non-proliferation context, ostensibly civilian research reactors have also been used to make plutonium for nuclear weapons, e.g. Cirus and Dhruva reactors in . The misuse of the Taiwan was planned. Is the Arak reactor in Iran in this category, ostensibly a civilian research reactor but in reality it would also have produced plutonium for nuclear weapons? • Propulsion reactors – either civilian or military • Production reactors – almost always military and dedicated to plutonium and tritium production for nuclear weapons, which means that the goal is the production of weapon- grade plutonium. Reactors

• Reactor types vary greatly, some are far simpler to build than others • Production reactors and research reactors are the simplest to build. • - and heavy -moderated reactors use natural fuel, so there is no need for uranium enrichment capabilities. These are usually the types sought by proliferant states to make plutonium for weapons. • Typically, commercial reactors use LEU and have much more advanced control and safety systems than production reactors We will consider three types of reactors in more detail I. Production Reactors II. Research Reactors III. Power Reactors I. Production Reactors

• There have been many types of production reactors, almost all of which are shut down. The few remaining operational ones are in India, , and Israel. • Their initial goal was to make weapon-grade plutonium for nuclear weapons. Later, some also have made tritium. • They typically were designed to use fuel. Some types, such as the Savannah River production reactors shifted to highly fuel in a driver/target system. • Fuel was simple, often uranium with simple cladding • They have been cooled by water, dioxide, or even air • Moderated typically by graphite or • Some also produced electricity Hanford : Graphite moderated, water cooled, natural uranium metal fuel http://www.hanford.gov/page.cfm/BReactor#BReactor Hanford B Reactor Initial power was 250 MWth

http://www.hanford.gov/page.cfm/BReactor#BReactor Hanford B Reactor Core Face http://response.restoration.noaa.gov/about/media/restoration-amid-hanfords-nuclear-waste-and-largest-environmental-cleanup- us.html Hanford Type Reactor: The design of First Plutonium Production Reactor Source DOE French G-2 Reactors, 250 MWth each Graphite moderated, fuel http://www.francetnp.fr/IMG/pdf/C-MAR_G1_G2_G3.pdf View of the G-2 reactor unit, with the fuel loading system in the foreground and the platform for the winches above the reactor http://www.francetnp.fr/IMG/pdf/C-MAR_G1_G2_G3.pdf French G-2 Reactor Savannah River Production Reactor

http://www.nationalregister.sc.gov/SurveyReports/HC02005.pdf Savannah River Production Reactor (K Reactor)

http://nonuclear.se/deltredici.f5.k.reactr.head.html Savannah River Production Reactor Source DOE II. Research Reactors

• Design and construction is relatively easy. • Some are similar to production reactors • Far simpler to build than power reactors • Fueled with LEU or HEU • Many can be used to make plutonium via a driver/target system China Advanced Research Reactor (CARR) is a tank in pool, water cooled, heavy water reflected, near 20% LEU fuel http://www.world-nuclear-news.org/NN-Chinese_research_reactor_starts_up-1805107.html Tehran Research Reactor

http://www.pbs.org/wgbh/pages/frontline/tehranbureau/2011/04/iran-plans-4-new-research-reactors-mousavi-aide-pressed-to-confess.html Tehran Research Reactor: Pool type, light water cooled and moderated http://www.nti.org/gsn/article/israel-would-not-warn-us-impending-iran-attack-official/ Arak Heavy Water Reactor

http://www.isisnucleariran.org/images/gallery/arak/25Nov2009.jpg Arak Heavy Water Reactor

http://en.wikipedia.org/wiki/File:Arak_Heavy_Water4.JPG Arak Heavy Water Reactor

http://www.presstv.ir/detail/2013/06/12/308556/arak-reactor-under-constant-iaea-watch/ Pool Type Research Reactor

http://www.ansto.gov.au/BusinessServices/OtherSpecialisedServices/Neutronactiviationanalysis/

Interior of OPAL reactor Australia III. Reactors

• There are many types of nuclear power reactors • The dominant types today are water-cooled and moderated, namely Pressurized Water Reactors (PWRs) and Boiling Water Reactors (BWRs). They both use LEU fuel and are expensive. • Another major type is the heavy water moderated and cooled CANDU reactor, which uses natural uranium fuel. • Older types include the reactor, advanced gas reactor, and the Russian RBMK reactor. • Breeder reactors have been built but have operated poorly. • Excluding breeder reactors, nuclear power reactors are an inefficient means of making weapon-grade plutonium, although they routinely make large quantities of reactor-grade plutonium, i.e. they discharge high fuel. • However, weapon-grade plutonium production is possible, albeit inefficient, in power reactors. Overview of Major Types of Power Reactors http://www.daviddarling.info/encyclopedia/N/nuclear_reactor.htm Boiling Water Reactors

https://www.asme.org/about-asme/who-we-are/engineering-history/landmarks/128-vallecitos-boiling-water-reactor

Vallecitos Boiling Water Reactor

http://www.euronuclear.org/info/encyclopedia/boilingwaterreactor.htm Pressurized Water Reactor

http://che.nelson.wisc.edu/cool_stuff/energy/nuclear.shtml Pressurized Water Reactor

http://www.nrc.gov/reading-rm/basic-ref/teachers/pwr-schematic.html CANDU Power Reactor

http://www.cna.ca/how_works/candu_technology/ CANDU Power Reactor

http://en.wikipedia.org/wiki/CANDU_reactor CANDU Power Reactor

http://www.newbrunswickbeacon.ca/29433/decade-refurbishment-nightmares-point-lepreau-online/

Point Lepreau CANDU Power Reactor

http://www.world-nuclear-news.org/C-Restart_of_Bruce_reactor_delayed-2105124.html

The hall of Bruce A unit 2 (Image: ) British Magnox Power Reactor

http://www.nda.gov.uk/news/oldbury-shutdown.cfm

Reactor 1 Oldbury British Magnox Power Reactor

http://www.world-nuclear-news.org/RS-Fuel_transfer_to_keep_Wylfa_1_running-0908124.html

Wylfa 1, the UK’s last operating Magnox reactor British Magnox Power Reactor

http://en.wikipedia.org/wiki/Magnox Russian RBMK Power Reactor

http://large.stanford.edu/courses/2013/ph241/kallman1/docs/nuclear_reactors.pdf Russian RBMK Power Reactor

http://www.globalsecurity.org/jhtml/jframe.html#http://www.globalsecurity.org/wmd/world/russia/images/rbmk-design.gif||| Russian RBMK Power Reactor

http://en.wikipedia.org/wiki/RBMK

Reactor hall of the RBMK-1500 at Ignalina Nuclear Power Plant, Lithuania – the upper biological shield (UBS) lies several meters below the floor of the reactor hall. Plutonium Production in Reactors

• Reactors are the principal method to make plutonium, whether deliberately or inadvertently. • The amount of plutonium produced in a reactor varies • Some reactors produce weapon-grade plutonium during normal operation; others produce reactor grade plutonium when operating normally. • All reactors can be used to make weapon-grade plutonium. Burnup of Irradiated Fuel and Plutonium Production • Burnup is a measure of the extent that uranium fuel has been irradiated in a reactor. • It is a measure of how much energy is extracted from a primary source, such as uranium, via fission. It is measured both as the fraction of fuel atoms that underwent fission and as the actual energy released per mass of initial fuel. • We will use the latter, namely the amount of energy released per unit of uranium. Its units are megawatt-thermal-days per tonne of uranium, e.g. MWth-d/tonne U, MWth-d/tonne, or MWth-d/t. • Be careful not to confuse MWth with MWe. MWe measures only a fraction of the total energy produced in the reactor. • Low burnup fuel, with values such as 500-1,000 MWth-d/tonne, would typically contain weapon-grade plutonium • High burnup fuel, with values such as 30,000 MWth-d/tonne typically would contain reactor-grade plutonium. (Note: MWD/MTU is same as MWth-d/t; and MTU equates to tonnes of uranium Source of slide: DOE Plutonium (Pu) Production at Normal (grams Pu per MWth-d, here called g Pu/MWD) Source: DOE Plutonium (Pu) Production at a fixed, but low burnup, 1000 MWth-d/tonne Source: DOE Simple Approximation of Annual Weapon-Grade Plutonium Production • In non-proliferation, it is useful to have a simple formula to estimate the amount of weapon-grade plutonium (about 93-95% plutonium 239) produced in natural uranium fueled reactors found in proliferant states, such as India, , and Iran. • This calculation is an approximation limited to weapon-grade plutonium production, i.e. low burnup irradiated fuel, and to reactors that use natural uranium fuel. • It should not be applied to nuclear power reactors using enriched uranium or to cases when higher burnup irradiated fuels are generated. • But with these limitations, the approximation is useful to understand the threat posed by the types of reactors encountered in non-proliferation cases. • When considering different reactors, the burnups associated with weapon- grade plutonium production can vary. For example, the burnup of the irradiated fuel from the Hanford B reactor would have a burnup of about 500- 600 MWth-d/tonne while a heavy water reactor would have a burnup of about 1000 MWth-d/tonne; yet both would produce weapon-grade plutonium with about the same fraction of plutonium 239. Simple Formula of Annual WGPu Production

Puyearly total = Pthermal power x C x 365 Days x PF

• Pthermal power equals the total energy ouput of the reactor, given as units of megawatt-thermal (MWth) – Yongbyon reactor- 10-20 MWth – Arak reactor in Iran – 40 MWth • C, or , is the total amount of energy produced by the reactor during a period of time divided by the amount of energy the plant would have produced at full power – Typical capacity factors are 0.5 or 50 percent, or 0.7, or 70 percent • PF, or plutonium conversion factor, converts the energy produced by the reactor into the amount of weapon-grade plutonium produced in the uranium fuel. The units are the mass of plutonium produced per energy produced by the reactor, i.e grams of plutonium per MWth-d, or grams/MWth-d. – For the production of weapon-grade plutonium, values of about 0.85- 0.9 grams/MWth-d are typical for a variety of reactors. Burnups will vary based on reactor type. Example of Annual WGPu Production

Pthermal power x C x 365 Days x PF • 20 MWth x 0.5 x 365 days x 0.9 grams/MWth-d • Answer = 3,285 grams/year, or 3.285 kilograms/year • Rounded to 3.3 kg/year Your Turn

• Yongbyon reactor, 10 MWth, 0.7 capacity factor, 365 days, 0.9 grams/MWth-d • Answer: 2,299 grams/year, or 2.3 kg/year • Arak reactor, 40 MWth, 0.7 capacity factor, 365 days, 0.9 grams/MWth-d • Answer: 9,198 grams/year (or about 9 kg/year) From Plutonium and Highly Enriched Uranium, 1996